Questions about Amba AHB

[amitgvlsijune06]

hello group,
i have few doubts in amba ahb waiting to be cleared.
1. why is HReady an inout for ahb slave.
2. when does Hgrant goes low during bus master transfer.
3. split and retry difference.

 

[tdminion]

amba ahb

not much talk about AHB??? Well, in case anyone still wants to know....


1) It's an input and output, NOT inout. The slave samples the HADDR when HSEL is active and HREADY is inactive.

2) HGRANTx should be inactive on the last ADDR phase (which is the 2nd from the last DATA phase). Also, if the slave performs a split or retry, the ARB may remove the GRANT.

3) The ARBITER uses the typical priority scheme when a RETRY is issued. If a SPLIT is issue, then the ARB may put the MASTER that was issued the RETRY (by a slave) into a lower priority. Thus giving other lower priority MASTERS a chance to utilize the bus.